Process and product for the stabilizing of unsaturated hydrocarbons



Patented Sept. 1, 1936 PATENT. OFFICE PROCESS PRODUCT FOR THE STA- BILIZING F UNSATURATED HYDRO- CARBONS Charles P. Wilson, .lr., Houston, Tex.

No Drawing. Continuation oi. application Serial No. 503,095, December 17, 1930. This application December 19, 1934, Serial No. 758,269

4 Claims.

This invention relates to a method of preventing deterioration of oils, fats, and rubber, and is applicable to substances liable to oxidation. The process and product will be described more particularly in relation to inhibiting auto-oxidation of motor fuels resulting from pyrolysis of heavy oils or coal.

Color deterioration and gum formation are known to be the result of oxidation. Color deterioration does not render motor fuel or motor 'oil unfit for use, but lowers its market value. Gum formation is the result of oxidation of unsaturated hydrocarbons, and when present inmotor fuel in small quantities renders the fuel unfit for use in an internal combustion engine. To obtain gum free and stable products, the' usual practice is to remove a substantial quantity of the unsaturated hydrocarbons through treatment with sulfuric acid, or through the control of the cracking plant in such a manner as not to produce a high concentration of the unstable unsaturated hydrocarbons. Control of the cracking process in this way sometimes results in a lower percentage of cracked fuel, and the sulfuric acid vents deterioration of hydrocarbons and variousoils liable to oxidation. It is particularly useful in the manufacture and marketing of motor fuel containing unsaturated hydrocarbons liable to oxidation, since it not only inhibits gum formation in storage, but actually reduces the gum yield when the cracked product to which the inhibitor has been added is tested for gum by the copper dish method. In the majority of cases only a minute quantity of the inhibitor, the cost of which is almost negligible, is required to reduce the result of the copper dish test to any desired specification. Results of tests made with identical cracked gasolines with and without the addition of the stabilizing compound are shown hereunder:

' Corrna Drsn Tns'rs Sample 1 Amoungigghibitor v Gum ($115 per 100 cc.) (gins. per 100 cc.)

Nil 0. 103 0. 002 0. 048 0. 005 0. 008 0. 018 0. 025

Sample 2 Nil 0. 183 0. 0007 0. 101 0. 0014 0. 066 0. 0035 0. 008 0. 007 0. 011

I have found that the following substances are effective in preventing gum formation when added in minute quantities to oils: pyrogallol, catechol, hydroquinone, ortho-aminophenol, para aminophenol, .para phenylenediamine, methylaminophenol, alpha-naphthol, 2-4-diaminophenol, l-amino 2 naphthol, 2-hydroxy- 5- aminotoluene, and p-dimethylaminophenol.

Numerous other compounds, such as cresol, dimethylaniline, etc., have a slight stabilizing effeet, but my experience has been that as a general rule only aromatic compounds with two hydroxyl and/or amino groups in the ortho or para positions of the benzene ring will completely prevent oxidation, although it will be noted. that alpha-naphthol, which has only one hydroxyl group, is an exception. The presence of other groups in the benzene ring in addition to the above mentioned does not destroy the inhibiting actions All of the above mentioned substances except alpha-naphthol are more soluble in water than in oil, in which they are nearly insoluble, and they are not satisfactory for use in practice for the commercial stabilization of motor fuels on account of the fact that it is difficult to prevent the latter from coming into contact with water.

Naphthol cannot be used, since it causes motor I vention are: the production of oil soluble oxidafuel to; deteriorate incolor, although it is satisfactory a regards solubility.

I ha e found that if an alkyl or aryl group is substituted for a hydrogen atom in these compounds, their solubility in water is decreased and 1 their solubility in oil is increased without an appreciable loss in their power to inhibit oxidation. The greater the number of akyl or aryl groups which can be substituted in the benzene ring, the

more soluble is the resulting compound in the-hy-.

drocarbon to be stabilized and the less soluble in water.

The new and novel features of the present intion inhibitors from certain types of oil insoluble phenolic or amino compounds, by substitution of cheaper thanthe pure unsaturated compounds,

but are equally satisfactory for the preparation of the substituted compound.

The introduction of alkyl groups may be effected by a modification of the method of Koenigs v (Ber. 23, 3144; 24, 179, 3889; 25, 2649) who prepared alkyl substituted phenols by allowing a mixture of one part of the phenol with the equivalent amount of an unsaturated hydrocarbon to stand for several days in the presence of one part of concentrated sulfuric acid and nine parts of acetic acid. My improvements that are new to the art in this method, using phenol as an illustration, are as follows:

1. The use of a mixture of unsaturated lhydrocarbons, such asturpentine, a liquid sulfur dioxide extract of an oil, or an oil derived from the pyrolysis of oil or coal. Such oils should preferably contain a large percentage of unsaturated hydrocarbons, as highconcentrations of the latter cause the reaction to take place more readily.

2. The use of dilute sulfuric acid (about 50%) instead of concentrated acid. This prevents loss of the phenolic compound by eliminating side reactions such as the formation of acetates.

3. The use of a much smaller quantity of sulfuric and acetic acid, thus reducing-the cost of manufacture.

4. Carrying out the reaction at an elevated temperature with agitation. This reduces the time required to a few hours.

5. The use of a considerable excess of unsatucompound during the washing is thus prevented.

It will be noted that by allcylation of the various oil insoluble oxidation inhibitors, such as pyrogallol and aminophenol, in various ways, an almost aosaeeo w infinite number of different compounds can be obtained which would be suitable for inhibiting the oxidation of oils. For the preparationof the various types of compounds, a number of different methods are available. For example, amyl pyjrogallol may be prepared by the action of amyl alcohol on pyrogallol in the presence of anhydrous zinc chloride; and aminophenol can be alkylated by heating under pressure with alcohols; or the reaction between pyrogallol and unsaturated hydr'ocarbons will take place to some extent withvout a catalyst, or with aluminium chloride. I

have, however, found that the cheapest and easiest compounds to manufacture are those prepared from pyrogallol by the method described above. Catechol also gives good results by this method, but is more expensive. Examples of'the preferred method of preparation using cracked distillate andturp'entine are given below:

Eive parts by weight of powdered pyrogallol,

ten parts of glacial acetic acid. one part of 50% sulfuric acid, and ten parts of cracked distillate are placed in an acid-resisting container fitted with a stirrer and a reflux condenser, and supplied with facilities for heating. The mixture is agitated violently, and heated to boiling. The agitation and heating are continued for two hours, 75 parts of cracked distillate being gradually added during this period. After two hours, whensubstantially all of the pyrogalloi shouldhave entered into combination with the unsaturated lwdrocarbons present, the agitation is stopped and the product allowed to cool in an oxygenfree atmosphere.

The reaction which occurs is probably as'follows: RCH=CH2+CsHs (OH) 3 olefine pyrogallol =RCH2.CH2.C6H2(OH) 3 stabilizer The resulting mixture consists of a solution ofthe oxidation inhibitor and acetic acid in the oil which supplied the unsaturated hydrocarbons, and a layer of sludge on the bottom of the containing vessel. Twenty parts of 0.1% sulfuric acid are introduced, and the mixture is agitated for fifteen minutes for the purpose of removing excess acetic acid. The washing also causes any substituted compound contained in the sludge to return to the oil solution. The lower layer is drained oil, and the extraction repeated twice.. 4

The solution of oxidation inhibitor thus prepared is then run into a. storage vessel, preferably of copper or wood.

When turpentine is used, forty parts of pyro- V gallol are dissolved by heating and agitation insixty parts of glacial acetic acid. One part of 50% sulfuric acid is added, and a hundred parts fresh turpentine introduced while the mixture is being agitated. Heat is evolved, and care must be taken that the temperature does not rise above amount of the substituted compound formed is substantially twice the weight of pyrogallol used.

I have found that acetic acid acts as a preservative of the compound, but most ofit must be removed, as it would cause the motor fuel to which the above described inhibitor has been added to become corrosive. The acetic acid may be removed by extraction with any suitable sol-.

vent, such as water or a mineral acid, or by other suitable methods such as distillation, instead of by dilute sulfuricacid as described in the above examples.

While the foregoing description has had particular reference to the invention as applied to polyhydric phenol compounds, it should be understood that the invention is also applicable to aromatic amines and aminophenols. The invention is furthermore not limited to the use of the modified Koenigs reaction, for it has been observed that improved inhibitors of the same type may be prepared by other methods without the use of catalysts. When using an active unsaturated hydrocarbon oil improved results may be obtained with phenols, aromatic amines or aminophenols by using heat or heat and pressure, whereby reaction between the unsaturated hydrocarbons and the phenol, amine or aminophenol occurs to form reaction products presumably of the nature of substituted derivatives having components of the unsaturated hydrocarbon oil as substituent groups.

As applied to the preparation of compounds from an aminophenol and a commercial terpene hydrocarbon oil, such as oil of turpentine or ordinary commercial turpentine, the invention may be practiced by following the foregoing directions for employing amodifled Koenigs reaction; or the aminophenol or turpentine or a mixture of turpentine and cracked hydrocarbon oil may be heated with or without pressure for sufiicient time to obtain the desired results. Valuable inhibitor compounds have been obtained without catalysts by heating the materials under a reflux condenser, but better results may be obtained by using somewhat higher temperatures of the order of 300 to 600 F. and pressures of around 100 pounds. Compounds so formed are thought to include terpenyl aminophenols in which the terpene group may be substituted for hydrogen of the amino radical or hydrogen of the benzene ring. At lower temperatures and in the absence of catalysts the terpene group,

such as alpha-, or beta-pinene, appears to replace the hydrogens on the amino radical, while at higher temperatures, or in the presence of a catalyst such as acetic and sulfuric acids, the substitution on the benzene ring is believed to predominate.

The following example will illustrate one method of practicing the invention using an aminophenol and turpentine:

- Fifty parts of para-aminophenol are dissolved by warming in l00--parts'of glacial acetic acid. Two parts of 50%'sulfuric acid is added and a mixture of 100 parts of turpentine and 50 parts of cracked gasoline is introduced into the mixture with agitation. The temperature is maintained at about 80 to 100 C. until the reaction is complete, which will ordinarily require about 30 minutes. The product is cooled and further diluted with cracked gasoline. The mixtureis washed with very dilute mineral acid to remove the strong acids. The product may then be added to the gasoline to be inhibited as desired and in the amount required to produce a stable product.

It has been. found that the substituted compound when prepared as described above may be stored for a long period of time, at least as long as two years as shown by practical tests, without losing activity as a. stabilizer.

I have found that a compound as thus prepared is acidic and that it can be removed or destroyed by shaking with alkalies, such as sodium carbonate or caustic soda. It is, therefore, necessary to prevent the motor fuel from coming into contact with alkaline substances after the addition of the inhibitor. The compound is also destroyed by organic peroxides, and to pre- .vent this the motor fuel must be perfectly fresh and free from peroxides when the compound is added.

The gumcontent of samples 3 and 4 shown hereunder has been determined by the U. S.

The gum content oi Samples 1 and 2 hereinbefore described under "Copper dish tests was determined by evaporating 100 cc. of cracked gasoline on a steam bath. In this test the gasoline is exposed to atmospheric oxygen during the evaporation and although a sample of cracked gasoline gives a considerable residue by this method, .the same sample might be found to be entirely free from inherent gum as determined by the steam oven method.

Results of storage tests made on identical cracked gasolines, with and without addition of inhibitor, are given below. The samples consist of cracked gasoline stored in dark in glass bottles vented to atmosphere;

Sample No. 3

' g g g? ($115 Color Saybolt chromometer Time of storage (walks) Without With 0.001% Without With 0.001%

7 inhibitor inhibitor inhibitor inhibitor 1 Nil Nil plus 25 plus 25 3 25 5 25 25 7 25 25 10 25 25 25 25 19 25 25 2; plus 17 25 29 25 35 25 4l plus 24 47 22 59 23 65 23 71 25 77 83 23 Without with 0.0005% Without With 0.(1X)5% (wmks) inhibitor inhibitor inhibitor inhibitor 5 plus 25 9 25 13 25 19 25 24 25 30 25 36 25 42 plus 24 48 24 M 23 60 21 77 83 19 This application is a continuation-in-part of my co-pending application, Serial No. 730,729, flied June 15, 1934, which in turn is a continuation of Serial No. 503,095, filed Decemberl'l, 1930.

From the above description it will be evident that while I have described and claimed the preferred embodiment of the invention, it is to be 1. Themethod of treating cracked petroleum understood-that {reserve the right to make all changes properly falling within the spirit of the invention and without the ambit of the prior art.

' Obviously many modifications and variations of the invention, as hereinbetore set forth, may

be made without' departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the append ed claims.

I claim:

distillatea, normally tending to deteriorate and iorm'gurn on storage, which comprises reacting an aminophenoi with turpentine in the presence of a catalyst to form a mixture of substituted aminophenol derivatives and subjecting said distillate to' the action of asmall amount of said derivatives whereby such deterioration and gum formation are substantiaily retarded.

2. The method of treating cracked petroleum distillates, normally tending to deteriorate and form gum on storage, which comprises subjecting the distillate to the action of a small amount of a mixture of para-aminophenol derivatives, said derivatives'containing components or turpentine as substitirents, whereby said deterioration and gum formation are substantially retarded.

3.-A cracked hydrocarbon distillate, normally CHARLES P. WILSON, JR. 

